Accurate odorization control

ABSTRACT

A system is provided. The system includes one or more of a fuel media supply, coupled to a fuel media supply flow meter, configured to provide unodorized fuel media, an odorant supply, configured to provide odorant, coupled to a first actuator, configured to allow odorant flow at a first pressure when enabled and a second actuator, configured to allow odorant flow at a second pressure lower than the first pressure when enabled, a mixture receiver, coupled to the fuel media supply and the first and second actuators, configured to receive odorized fuel media comprising a mixture of the unodorized fuel media and the odorant and a control system, configured to initiate production of the mixture, adjust the mixture with the first and second actuators, in response to the mixture does not include a desired concentration of the odorant and terminate production of the mixture.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to earlier filed provisional application No. 63/337,659 filed May 3, 2022 and entitled “ACCURATE ODORIZATION CONTROL”, the entire contents of which are hereby incorporated by reference.

FIELD

The present invention is directed to apparatuses and systems for adding odorant to propane and natural gas media. In particular, the present invention is directed to apparatuses and systems for efficiently metering and delivering odorant blends to achieve desired injection rates.

BACKGROUND

Natural gas processing begins at a well head. The composition of raw natural gas extracted from producing wells depends on the type, depth, and location of the underground deposit and the geology of the area. Oil and natural gas are often found together in the same reservoir. The natural gas produced from oil wells is generally classified as associated-dissolved gas meaning that the gas had been associated with or dissolved in crude oil. Natural gas production not associated with crude oil is classified as “non-associated.” In 2009, 89 percent of U.S. wellhead production of natural gas was non-associated.

Natural gas processing plants purify raw natural gas by removing contaminants such as solids, water, carbon dioxide (CO2), hydrogen sulfide (H₂S), mercury, and higher molecular mass hydrocarbons. Some of the substances which contaminate natural gas have economic value and are further processed or sold. An operational natural gas plant delivers pipeline-quality dry natural gas that can be used as fuel by residential, commercial, and industrial consumers, or as a feedstock for chemical synthesis.

Odorants may be added to odorless gases, such as natural gas or propane, so that they can be detected easily by human smell. Conventional odorants include mercaptans, methyl sulfides, aliphatic sulfides, dimethylsulfide as well as various blends of other commonly accepted chemicals. Odorants that may be used with natural gas are extremely odiferous and volatile, so that only a small amount of concentrated liquid is needed to odorize a relatively large volume of natural gas or propane. Odorants used for natural gas or propane may vary from country to country, depending on gas distribution regulations. Some odorants may contain sulfur, which is oxidized to sulfur dioxide when the gas is burned. For very high volume systems (and for some smaller volume systems), liquid injection odorizers are being manufactured. These odorizers work by the addition of small amounts of liquid odorant to moving gas. A pump that can be controlled to give the range of addition rates necessary may be an important aspect of this type of odorizer. Computer control to monitor flow rates and vary injection rate is a significant part of the more modern versions of this.

An odorizer is a device that adds an odorant to a gas. The most common type is one that adds a mercaptan liquid into natural gas or propane distribution systems so that leaks can be readily detected. Other types have been used for carbon dioxide fire extinguishers. Equipment that provides natural gas odorization runs the gamut from a simple wick in a container to computerized equipment, which controls the amount of odorant based on flow rate, tracks the amount of odorant in inventory, and may generate alarms when odorant is not being injected into the gas stream.

Various techniques have been developed for odorizing natural gas. One technique consists of injecting liquid odorant directly into natural gas pipelines. A high pressure injection pump draws odorants from a liquid storage tank into the gas pipeline where the odorants evaporate throughout the gas in the pipeline. Liquid odorant pressure is typically stepped down in the injection system and the released pressure is directed into an expansion tank. At regular intervals, gas may be released from the expansion tank so as to maintain the pressure within the expansion tank under a predetermined pressure threshold. The gas released from the expansion tank may be typically passed through a filter before being discharged as an odorant-free gas.

SUMMARY

In accordance with embodiments of the present invention, a system is provided. The system includes one or more of a fuel media supply, coupled to a fuel media supply flow meter, configured to provide unodorized fuel media, an odorant supply, configured to provide odorant, coupled to a first actuator, configured to allow odorant flow at a first pressure when enabled and a second actuator, configured to allow odorant flow at a second pressure lower than the first pressure when enabled, a mixture receiver, coupled to the fuel media supply and the first and second actuators, configured to receive odorized fuel media comprising a mixture of the unodorized fuel media and the odorant and a control system, configured to initiate production of the mixture, adjust the mixture with the first and second actuators, in response to the mixture does not include a desired concentration of the odorant and terminate production of the mixture.

In accordance with embodiments of the present invention, a method is provided. The method includes one or more of initiating production of a mixture comprising unodorized fuel media and an odorant, adjusting the mixture with a first and a second actuator, in response to the mixture does not include a desired concentration of the odorant, the first actuator configured to allow odorant flow at a first pressure when enabled and the second actuator configured to allow odorant flow at a second pressure lower than the first pressure when enabled, and terminating production of the mixture.

An advantage of the present invention is it provides a method to accurately and repeatedly meter odorant into propane or gas media. Odorant concentrations must be strictly maintained in order for the odorant to be effective while not harming individuals, pets, clothing, or property.

Another advantage of the present invention is it provides an automated process to control odorant concentration and eliminate human error during a mixing process. The mixing process may be based on either flow rate or volume.

Yet another advantage of the present invention is it provides both a maximum flow and a reduced flow odorant supply loop. The maximum flow supply loop allows for great efficiency to odorize a large amount of bulk media. The reduced flow supply loop allows for great accuracy to provide a desired concentration level.

Additional features and advantages of embodiments of the present invention will become more readily apparent from the following description, particularly when taken together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration depicting an odorized fuel delivery system in accordance with embodiments of the present invention.

FIG. 2 is an illustration depicting a mechanical system in accordance with embodiments of the present invention.

FIG. 3 is an illustration depicting a control system in accordance with embodiments of the present invention.

FIG. 4 is a flowchart depicting a flow rate-based process in accordance with embodiments of the present invention.

FIG. 5 is a flowchart depicting a volume-based process in accordance with embodiments of the present invention.

FIG. 6 is an exemplary illustration depicting first and second modulation of first and second actuators in accordance with embodiments of the present invention.

DETAILED DESCRIPTION

The present invention is directed to devices and systems for odorizing bulk propane or gas media. The devices and systems provide improved flexibility for metered concentrations of odorant within bulk propane or gas. Odorants such as Mercaptan are combined with bulk media in concentrations of approximately a part per billion. Such concentrations allow the presence of otherwise odorless gases to be readily detected by individuals without harming people, animals, or property.

Referring now to FIG. 1 , an illustration depicting an odorized fuel delivery system 100 in accordance with embodiments of the present invention is shown. The odorized fuel delivery system 100 may provide odorized fuel media 168 to a mixture receiver 124, which may include a propane delivery truck (shown), a propane or gas pipeline, a vessel or tank for storing odorized fuel media, or another odorized gas endpoint. Odorant stored in an odorant supply 116 may be combined with bulk propane or natural gas stored in a fuel media supply 120 and stored to the mixture receiver 124, as further described herein.

The odorized fuel delivery system 100 may include a control system 104 and a mechanical system 108 that operate cooperatively to measure flow rates and regulate pressurized odorant 164. The control system 104 is described in more detail with respect to FIG. 3 and the mechanical system 108 is described in more detail with respect to FIG. 2 . The control system 104 receives a fuel side flow amount 140 from a flow meter 136 and an odorant side flow amount 144 from the mechanical system 108 and in response produces flow controls 148 to the mechanical system 108. The flow controls 148 control the operation of odorant actuators within the mechanical system 108 to regulate pressurized odorant 156 flow. The mechanical system 108 receives pressurized odorant 156 from an odorant supply 116 and the flow controls 148 from the control system 104 and produces regulated pressurized odorant 164 and the odorant side flow amount 144 to the control system 104.

On the odorant supply side, a pressurized gas supply 112 is coupled to the odorant supply 116 and provides pressurized gas 152 (e.g., at 115-120 psi) at a higher pressure than the odorant supply 116. In one embodiment, the pressurized gas 152 may be nitrogen. In another embodiment, the pressurized gas 152 may be methane. The pressurized gas supply 112 typically pressurizes the odorant supply 116 to a range between 30 and 55 pounds per square inch (psi). In one embodiment, the pressurized gas supply 152 may pressure odorant in the odorant supply 116 to approximately 15-20 psi over a set pressure of the media being injected into. For example, if the fuel media supply 120 is pressurized to 100 psi (measured at the junction point of the unodorized fuel media 160 and the regulated pressurized odorant 164), the pressurized gas 152 pressures the odorant supply 116 to about 115-120 psi. This pressure differential between the fuel media supply 120 and the odorant supply 116 is what “powers” the liquid chemical movement through the system. Once pressure is blanketing the chemical in the odorant supply 116, the actuators in the mechanical system 108 act as an on/off control for the movement of the liquid chemical odorant.

On the media supply side, bulk propane or natural gas is stored in an un-odorized state in the fuel media supply 120. There are three valves 128 shown in FIG. 1 —a first valve 128A at the output of the fuel media supply 120, a second valve 128B at the input to the mixture receiver 124, and a third valve 128C at the output of the odorant supply 116. In operation, all three valves 128 may be in an open state to allow odorant and media movement.

In one embodiment (described in more detail in FIG. 4 ), odorized fuel delivery may be initiated by opening valve 128A at the fuel media supply 120. This causes flow of unodorized fuel media 160 through a gas pipe. A flow meter 136 measures flow of the unodorized fuel media 160 and provides a fuel side flow amount 140 to the control system 104. The fuel side flow amount 140 is a data item that reflects unodorized propane or gas flow measured by the flow meter 136. A processor 304 in the control system 104 detects the fuel side flow amount 140, and depending on the flow amount 140 may enable a flow control 148 to the mechanical system 108. Enabled flow controls 148 allow actuators in the mechanical system 108 to open and allow release of regulated pressurized odorant 164 through a check valve 132 to mix with the unodorized fuel media 160. The check valve 132 allows the regulated pressurized odorant 164 to flow in one direction only, and acts as a backflow valve that prevents either the unodorized fuel media 160 or the odorized fuel media 168 flowing back into the mechanical system 108. The product of the mixture is odorized fuel media 168, which flows under pressure through valve 128B and enters the mixture receiver 124.

In one embodiment, the valves 128 may be opened and closed in sequence. For example, in one embodiment all three valves 128 are initially closed to block flow. Valve 128C may be opened first in order to charge pressurized odorant 156 to the mechanical system 108. Next, valve 128B may be opened to allow odorized fuel media 168 to flow into the mixture receiver 124. Finally, valve 128A may be opened to allow unodorized fuel media 160 to flow. At this point, all of valves 128A-C are opened and the mixture receiver 124 is being filled with odorized fuel media 168.

When the mixture receiver 124 has reached a desired level (e.g., full or some level below that), first valve 128B is closed. This stops flow of odorized fuel media 168 into the mixture receiver 124. Next, valve 128A is closed to disable the flow of unodorized fuel media 160. This will thereby cause the flow meter 136 to report a reduced or declining fuel side flow amount 140, which in turn causes the control system 104 to disable flow controls 148 to the mechanical system 108 and reduce or stop the flow of regulated pressurized odorant 164. At this point, valve 128C may be closed to stop pressurized odorant 156 from passing from the odorant supply 116 to the mechanical system 108. At this point all valves 128A-C have been closed and a mixing and transfer operation of the system 100 is completed.

Referring now to FIG. 2 , an illustration depicting a mechanical system 108 in accordance with embodiments of the present invention is shown. The mechanical system 108 includes various pathways, actuators, and instruments for the odorant. The pressurized odorant 156 is received by an inlet filter 204, which removes various impurities (e.g., rust, metal, dust, manufacturing debris, welding slag from bulk tanks and odorant transfer lines, pipe epoxy, PTFE tape, etc.) from the pressurized odorant 156. The pressurized odorant 156 passes to a pressure regulator 208, which restricts flow to approximately 5 pounds per square inch (psi) over the injection vessel media pressure (i.e., the fuel side flow amount 140) in order to maintain a higher pressure than the injection point to facilitate liquid movement. Flow will proceed from the source to the mixture receiver 124 because liquids will flow from higher pressure to lower pressure. In one embodiment, a pressure gauge 212 may be coupled to the pressure regulator 208 to display a current pressure of the pressurized odorant 156 to an operator. This may allow an operator, for example, to observe a low pressure reading which may suggest the pressurized gas supply 112 needs to be replaced.

The pressurized odorant 156 passes through gas tubing 216 and may be sampled by a flow meter 220. The flow meter 220 measures the flow rate of the pressurized odorant 156, and generates an odorant side flow amount 144 data reading to the control system 104. Next, the pressurized odorant 156 passes through a flow indicator 224, which an operator may observe to verify that pressurized odorant 156 is currently flowing. For example, if an operator believes that pressurized odorant 156 should be flowing but the flow indicator 224 reflects no flow, this may suggest that either the valve 128C is closed, the pressurized gas supply 112 is out of nitrogen or methane, or the odorant supply 116 may be empty.

From the flow indicator 224, the pressurized odorant 156 passes to two or more actuators 228. In the preferred embodiment, there may be two actuators 228 in the mechanical system 108: a maximum flow actuator 228A and a reduced flow actuator 228B. In other embodiments there may be other actuators 228 present that may regulate pressurized odorant 156 flow in other ways. In one embodiment, the maximum flow actuator 228A and the reduced flow actuator 228B may be solenoids. Solenoids are electronically controlled valves that are controlled by the processor of the control system 104. Other forms of electronic actuators knows in the art may be used as alternatives to solenoids. The maximum flow actuator 228A functions as a switch that is controlled by one of the flow controls 148. When the corresponding flow control 148 is enabled, the maximum flow actuator 228A allows the pressurized odorant 156 to flow at a maximum pressure level to an odorizer outlet to an injection point 236. The injection point 236 is a location at which the odorant is introduced to and mixed with an unodorized fluid or gas. In one embodiment, the maximum pressure level may be the pressure level of the odorant supply 116. The reduced flow actuator 228B functions as a switch that is controlled by another of the flow controls 148. When the corresponding flow control 148 is enabled, the reduced flow actuator 228B allows the pressurized odorant 156 to flow at a reduced pressure level to an odorizer outlet to the injection point 236. In one embodiment, the reduced flow rate may be determined by a metering valve 232 in the same reduced flow portion of the mechanical system 108 as the reduced flow actuator 228B. In one embodiment, the metering valve 232 may be manually set during installation (e.g., to a predetermined % of the maximum flow rate through the maximum flow actuator 228A, such as 10%).

To set the metering valve 232 correctly, the metering valve 232 is initially closed completely. An operator may then activate a control on the control system 104 to select a flow control 148 that enables only the reduced flow actuator 228B. The operator may manually open the metering valve 232 until the odorant has enough of a flow rate as measured by the metering valve 232 to meet the user's injection needs. The operator then inactivates the control on the control system 104 to deselect the flow control 148 for the reduced flow actuator 228B. This causes the flow of regulated pressurized odorant 164 to stop. With the metering valve 232 now set, the operator may place the control system 104 in a normal automatic flow-based operating mode where the flow controls 148 are controlled by the fuel side flow amount 140 from flow meter 136.

Given the dual path structure of the present invention, the system 100 will always have redundancy. The second (high flow) injection leg does not have or require an associated metering valve 232. During operation, if the odorant flow rate is not high enough to meet injection standards using the initial metering valve 232 test, the control system 104 may activate the maximum flow actuator 228A (with a flow control signal 148) to open and accommodate accurate injection rates. In another embodiment, a metering valve 232 may be set with a motor encoder combination that may be programmed and controlled by the control system 104.

In one embodiment, the desired concentration may be ½ lb. of odorant per 1 million standard ft.³ of unodorized media. In one embodiment, the metering valve 232 may be set to a flow of approximately 10% of a maximum odorant flow rate through the maximum flow actuator 228A. In one embodiment, the maximum flow actuator 228A may be enabled at the same time or a different time as the reduced flow actuator 228B. Typically, a fuel mixing and transfer operation is performed in one of two ways. A flow rate-based process is shown and described with respect to FIG. 4 while a volume-based process is shown and described with respect to FIG. 5 .

Referring now to FIG. 3 , an illustration depicting a control system 104 in accordance with embodiments of the present invention is shown. The control system 104 may include one or more processors 304 and one or more memory devices 308, although a single processor 304 and memory device 308 are shown in FIG. 3 . Processors 304 may include any processors know in the art, including microprocessors, microcontrollers, field-programmable gate arrays (FPGAs), or any other form of hardware or software processors. Memory 308 may include any combination of volatile or non-volatile memories known in the art, and may store one or more software applications 312 and associated data 316. In one embodiment, the processor 304 may be a programmable logic controller (PLC).

In one embodiment, the control system 104 may include one or more controls 324 and a display 328. The controls 324 provide a selected control 332 signal to the processor 304 and may allow an operator to power-on/off the control system 104, switch between manual and automatic operating modes, enter media and/or odorant volumes, flow rates, and/or operating times, and manually enable/disable actuators 228A/228B. The controls 324 may include a numeric keypad, an alphanumeric keyboard, and/or individual selection buttons or other controls. The display 328 receives displayed information 336 from the processor 304 and may provide individual numeric or alphanumeric indicators and/or a display panel such as an LCD panel. In one embodiment, the LCD panel may include a touchscreen feature that may allow the display 328 to also include the controls 324. The displayed information 336 may indicate an on/off status of the control system 104, a detected fault, a manual/automatic operating mode, a current setting for the metering valve 232, a reading of the pressure gauge 212, a manual enable/disable status of the actuators 228A/228B, the fuel side flow amount 140, the odorant side flow amount 144, open/closed status of valves 128, volume of odorized propane or natural gas provided to a current mixture receiver 124, and/or volume of odorized propane or natural gas remaining to be provided to the mixture receiver 124. The display 328 may additionally show an operator any of power status, operating status, flow rates, gas or odorant volumes, elapsed time, remaining time, temperatures, malfunctions/failures, and the like.

One or more applications 312 are stored in the memory 308 and executed by the processor 304 to generate the flow controls 148. The flow controls 148 may include an enable maximum flow 340A signal and an enable reduced flow 340B signal. The enable maximum flow 340A signal controls the maximum flow actuator 228A and the enable reduced flow 340B signal controls the reduced flow actuator 228B. The processor 304 receives flow meter data 320, which may include the fuel side flow amount 140 and the odorant side flow amount 144. The processor 304 may store the flow amounts 140, 144, selected controls 332, and current flow controls 148 as data 316 in the memory 308.

In one embodiment, the control system 104 may include other components not specifically shown and described herein. For example, the control system 104 may include one or more controls for various purposes, including but not limited to: powering the control system 104 or specific control system 104 components, opening or closing any of valves 128, initiating operation of the fuel delivery system 100, terminating operation of the fuel delivery system 100, enabling or disabling any of the flow controls 148, entering operator identifiers and/or passwords, entering timer values, and the like.

In one embodiment, the control system 104 may include other components to communicate remotely to receive or provide data through network interface(s). The network interfaces may be of any type, including but not limited to Ethernet, Wi-Fi, Bluetooth, RS-232, RS-422, and the like. In one embodiment, the controls 324 and displayed information 328 may be accessed remotely by an application running on a remote computer (e.g., desktop, server, or portable computer, smartphone, smartwatch, etc.) that accesses the control system 104 over a wired or wireless connection.

Referring now to FIG. 4 , a flowchart depicting a flow rate-based process 400 in accordance with embodiments of the present invention is shown. The flow rate-based process 400 shows operation steps for a primary embodiment of the present application. Flow begins at block 404.

At block 404, a valve 128A is opened to allow unodorized fuel media 160 to flow. Prior to this point, both the maximum flow actuator 228A and the reduced flow actuator 228B are preferably closed. The unodorized fuel media 160 is stored in a fuel media supply 120 and passes through the valve 128A and a flow meter 136. Flow continues to block 408.

At block 408, the fuel side flow amount 140 is continually measured. The flow meter 136 outputs the fuel side flow amount 140 signal to the control system 104 as flow meter data 320 to the processor 304. With the valve 128A opened, a positive fuel side flow amount 140 is reported to the processor 304. Flow continues to block 412.

At block 412, the reduced flow actuator 228B is opened. This allows pressurized odorant 156 to flow through the inlet filter 204, the pressure regulator 208, the gas tubing 216, the flow meter 220, the flow indicator 224, the reduced flow actuator 228B, the metering valve 232 and the odorizer outlet to injection point 236 as regulated pressurized odorant 164. In one embodiment, the processor 304 may enable a reduced flow signal 340B as a flow control 148 to the reduced flow actuator 228B in response to receiving a positive fuel side flow amount 140, without any additional comparison. In another embodiment, in response to receiving the positive fuel side flow amount 140 from the flow meter 136, the processor 304 may compare the fuel side flow amount 140 to a reduced flow threshold stored in the data 316. If the fuel side flow amount 140 is greater than or equal to the reduced flow threshold, the processor 304 may generate the enable reduced flow 340B signal. If the fuel side flow amount 140 is initially too low to trigger the enable reduced flow signal 340B, if the fuel side flow amount 140 increases above the reduced flow threshold, the processor 304 may enable the reduced flow signal 340B. Flow continues to block 416.

At block 416, the odorant side flow amount 144 is measured. The flow meter 220 outputs the odorant side flow amount 144 signal as flow meter data 320 to the processor 304. A positive value odorant side flow amount 144 is produced by the flow meter 220 in response to the reduced flow actuator 228B is opened and the metering valve 232 is set to allow a positive odorant flow. Flow continues to decision block 420.

At decision block 420, the processor 304 determines if there is a desired odorant concentration in the odorized fuel media 168. The processor 304 compares the odorant side flow amount 144 to the fuel side flow amount 140 to determine the odorant concentration. In one embodiment, a desired odorant concentration may be ½ lb. of odorant per 1 million standard ft.³ of unodorized fuel media. In another embodiment, a desired odorant concentration may be within a range of ½ lb. of odorant per 1 million standard ft.³ of unodorized fuel media. The range may be a predetermined amount or percentage difference from ½ lb. of odorant per 1 million standard ft.³ of unodorized fuel media (e.g., 1.49-1.51 lb of odorant, +/−0.5% difference from the ½ lb. of odorant nominal value, etc.). Specific range values are known in the art as being affective for the distribution of odorized fuel media. If the desired odorant concentration has been reached, then flow proceeds to decision block 436. If the desired odorant concentration has not been reached (i.e., the odorant concentration is either too high or too low), then flow proceeds to decision block 424.

At decision block 424, the processor 304 determines if the odorant concentration is high or low. The odorant concentration may be stable, increasing, or decreasing. The processor 304 may calculate odorant concentration at either regular or varying intervals while there is a positive flow of regulated pressurized odorant 164. In one embodiment, the processor 304 may calculate odorant concentration every half second, every second, every 10 seconds, or every minute, for example. In another embodiment, the processor 304 may calculate odorant concentration at time intervals based on a calculated difference from a nominal concentration value (e.g., ½ lb. of odorant per 1 million standard ft.³ of unodorized fuel media). For example, odorant concentration may be measured every minute for concentrations within 0.1% of a nominal value, every 10 seconds for concentrations within 0.5%-0.1% of the nominal value, and every second for concentrations >0.5% of the nominal value.

In a continuous flow environment (not-batching), if the odorant concentration is too high, the processor 304 may temporarily disable the flow controls 148 (thus disabling the maximum flow actuator 228A and the reduced flow actuator 228B) until a quantity of unodorized fuel media 160 has passed the odorized outlet to injection point 236. The processor continuously monitors the fuel side flow amount 140 from the flow meter 136, and calculates the odorant concentration. With the unodorized fuel media 160 continuing to flow and the regulated pressurized odorant now inhibited, the odorant concentration decreases in the odorized fuel media 168. When the proper odorant concentration has been reached, the processor 304 may enable the reduced flow actuator 228B.

In a batching environment, the odorant concentration is monitored and adjusted as shown in FIG. 4 . If the processor 304 determines the odorant concentration is too high, then the processor 304 may need to reduce the odorant concentration and flow proceeds to block 428. If the processor 304 determines the odorant concentration is too low, then the processor 304 needs to increase the odorant concentration and flow proceeds to block 432.

At block 428, the processor 304 pulses the reduced flow actuator 228B. Pulsing the reduced flow actuator 428 reduces the average odorant flow rate through the reduced flow actuator 228B compared to the reduced flow actuator 428 being enabled (i.e., without pulsing), thereby increasing the odorant concentration at a slower rate. In one embodiment, the processor 304 alternates the enable reduced flow 340B signal between an enabled state and a disabled state at a fixed duty cycle (e.g., 50%). In another embodiment, the processor 304 alternates the enable reduced flow 340B signal between an enabled state and a disabled state at a variable duty cycle (e.g., 10-50%), based on a difference between a calculated odorant concentration and a nominal concentration value. For example, the processor 304 may pulse the reduced flow actuator 228B at a 10% duty cycle for a difference between the calculated odorant concentration and the nominal odorant concentration of 0.1% or less, at a 20% duty rate for a difference of 0.5%-0.1%, and at a 50% duty cycle for a difference >0.5%. Flow proceeds to decision block 420 to determine if the current odorant concentration is a desired odorant concentration.

At block 432, the processor 304 pulses the maximum flow actuator 228A. Pulsing the maximum flow actuator 432 increases the average odorant flow rate and therefore, the odorant concentration. When the processor 304 pulses the maximum flow actuator 228A, the odorant concentration increases faster than when the reduced flow actuator 228B is pulsed. In one embodiment, the processor 304 alternates the enable maximum flow 340A signal between an enabled state and a disabled state at a fixed duty cycle (e.g., 50%). In another embodiment, the processor 304 alternates the enable maximum flow 340A signal between an enabled state and a disabled state at a variable duty cycle (e.g., 10-50%), based on a difference between a calculated odorant concentration and a nominal concentration value. For example, the processor 304 may pulse the maximum flow actuator 228A at a 10% duty cycle for a difference between the calculated odorant concentration and the nominal odorant concentration of 0.1% or less, at a 20% duty rate for a difference of 0.5%-0.1%, and at a 50% duty cycle for a difference >0.5%. Flow proceeds to decision block 420 to determine if the current odorant concentration is a desired odorant concentration.

At decision block 436, the processor 304 determines if the fuel flow is stopped. Fuel flow is stopped if the processor 304 observes a zero fuel side flow amount 140 from the flow meter 136. This may indicate there is no more flow of unodorized fuel media 160 through the flow meter 136 due to valve 128A becoming closed or the fuel media supply 120 being empty. In one embodiment, the fuel side flow amount 140 may not stop, but may fall below a fuel flow low threshold stored in data 316. The processor 304 may compare the fuel side flow amount 140 to the fuel flow low threshold. If the fuel side flow amount 140 falls below the fuel flow low threshold, the processor 304 may determine the flow of unodorized fuel media 160 has (effectively) stopped. Flow continues to block 440.

At block 440, the processor 304 closes the maximum flow actuator 228A and the reduced flow actuator 228B. The processor 304 closes the maximum flow actuator 228A by disabling the enable maximum flow 340A signal and closes the reduced flow actuator 228B by disabling the enable reduced flow 340B signal. With both actuators 228A, 228B now closed, the flow of regulated pressurized odorant 164 is disabled. Flow ends at block 440.

Referring now to FIG. 5 , a flowchart depicting a volume-based process 500 in accordance with embodiments of the present invention is shown. The volume-based process 500 shows operation steps for a secondary embodiment of the present application. Flow begins at block 504.

At block 504, a volume of bulk or odorized media to process is specified. In one embodiment, an operator may enter the volume to be odorized on a control panel of the control system 104, using controls 324 and/or display 328. In another embodiment, an operator may enter the volume to be odorized on a remote computing device connected to the processor 304 through a wired or wireless network interface, and the remote computing device may provide the volume to the processor 304. In another embodiment, a server or other remote computing device may provide the volume to be odorized to the processor 304 through the wired or wireless network interface. In one embodiment, the volume of fuel media to process may correspond to a volume of the fuel media supply 120. In another embodiment, the volume of fuel media to process may correspond to a volume of a mixture receiver 124. In another embodiment, the volume of fuel media to process may correspond to a desired volume of odorized media to add to a mixture receiver 124. Flow proceeds to block 508.

At block 508, the processor 304 calculates an odorant volume. The odorant volume 508 may be based on a desired concentration of odorant within the odorized fuel media 160, such as ½ lb. of odorant per 1 million standard ft.³ of unodorized fuel media. In one embodiment, the processor 304 may calculate the odorant volume by multiplying the volume of fuel media to process from block 504 by the desired concentration. Flow proceeds to block 512.

At block 512, a valve 128A is opened to allow unodorized fuel media 160 flow. In one embodiment, an operator manually opens valve 128A. Flow proceeds to block 516.

At block 516, the reduced flow actuator 228B is opened. The processor 304 transmits the enable reduced flow 340B signal to the reduced flow actuator 228B, and in response the reduced flow actuator 228B opens and allows odorant to flow through the metering valve 232. This allows the reduced odorant flow as regulated pressurized odorant 164. Flow continues to optional block 520 and block 524.

At optional block 520, the maximum flow actuator 228A is opened. The processor 304 transmits the enable maximum flow 340A signal to the maximum flow actuator 228A, and in response the maximum flow actuator 228A opens and allows odorant to flow. Enabling the maximum flow actuator 228A as well as the reduced flow actuator 228B allows the most odorant flow through the system as regulated pressurized odorant 164. Flow continues to block 524.

At block 524, a designated percentage of unodorized fuel media 160 or odorized fuel media 168 volume is produced. In one embodiment, the designated percentage may be close to the volume specified in block 504. For example, the designated percentage may be 90% of the volume required. The designated percentage may be any value, but is preferably chosen in order to maximize odorization efficiency for the current batch/volume while preventing volume overrun through the maximum flow actuator 228A. In one embodiment, the designated percentage of unodorized fuel media 160 or odorized fuel media 168 volume may depend on the volume of a mixture receiver 124. For example, it may be desirable to only fill a delivery truck 124 to a less than full capacity (e.g., 30%) because of a purchased volume not needing the entire capacity of the delivery truck 124. Flow continues to block 528.

At block 528, the processor 304 closes the maximum flow actuator 228A by disabling the enable maximum flow 340A signal. With the maximum flow actuator 228A now closed/disabled, the only continuing odorant flow is due to the reduced flow actuator 228B. Flow continues to block 532.

At block 532, the processor 304 measures odorant flow and volume. The mechanical system 108 may include a flow meter 220 that produces an odorant side flow amount 144 and an odorant volume to the processor 304. Flow continues to decision block 536.

At decision block 536, the processor 304 determines if a desired odorant volume has been provided. In another embodiment, the processor 304 may compare the received odorant side flow amount 144 and an odorant volume from the flow meter 220 and compare to a desired odorant volume. For example, the desired odorant volume may be stored in data 316 for batches of odorized fuel media 160 of a standard size. As another example, given a known desired odorant concentration level, the processor 304 may determine the desired odorant volume by multiplying the volume of odorized media to process from block 504 by the known desired odorant concentration level. If the desired odorant volume has not been provided, then flow proceeds to decision block 536 to continue checking. If the desired odorant volume has been provided, then flow proceeds to block 540.

At block 540, the desired odorant volume has been provided and the processor 304 closes the reduced flow actuator 228B by disabling the enable reduced flow 340B signal. With both the reduced flow actuator 228B and the maximum flow actuator 228A now closed/disabled, no odorant continues to flow in the system and the volume-based process is now completed. Flow ends at block 540.

Referring now to FIG. 6 , an exemplary illustration depicting a first and second modulation of first and second actuators in accordance with embodiments of the present invention is shown. The first and second modulations apply when the odorant concentration is not at a desired level or within a desired range. The first modulation is applied to the first actuator (i.e., the maximum flow actuator 228A) when the odorant concentration is too low. The second modulation is applied to the second actuator (i.e., the reduced flow actuator 228B) when the odorant concentration is too high. The control system 104 continuously calculates odorant concentration in the odorized fuel media 168. The odorant concentration is based on a ratio of the fuel side flow amount 140 compared to the odorant side flow amount 144.

In one embodiment, the valve 128A is open and the flow meter 136 detects a positive flow side fuel amount 140. The processor 304 receives the fuel side flow amount 140 and enables the reduced odorant flow 340B signal to the reduced flow actuator 228B. This causes a reduced flow of odorant to the odorized fuel media 168.

The processor 304 determines the actual odorant concentration, as discussed herein, and compares the actual odorant concentration to a desired odorant concentration stored in data 316. In the presented example, the actual odorant concentration is less than the desired odorant concentration. The processor 304 enables the maximum flow signal 340A and enables the maximum flow actuator 228A with the first modulation. In the presented example, the first modulation may have a fixed duty cycle and period that selectively enables and disables the maximum flow actuator 228A. The processor 304 may continue to monitor and calculate the actual odorant concentration while the first modulation is occurring. The processor 304 may determine the actual odorant concentration is increasing and may become equal to the desired odorant concentration. At that point, the processor 304 may discontinue the first modulation.

The actual odorant concentration may continue to increase to a level that is greater than the desired odorant concentration. The processor 304 may enable the second modulation by enabling the reduced flow signal 340B to the reduced flow actuator 228B with the second modulation. In the presented example, the second modulation may have a fixed duty cycle and period that selectively enables and disables the reduced flow actuator 228B. The processor 304 may continue to monitor and calculate the actual odorant concentration while the second modulation is occurring. The processor 304 may determine the actual odorant concentration is decreasing and may become equal to the desired odorant concentration. At that point, the processor 304 may discontinue the second modulation.

The actual odorant concentration may continue to decrease to a level that is equal to the desired odorant concentration. The processor 304 may discontinue the second modulation by returning the reduced flow signal 340B to the reduced flow actuator 228B with an “on” or enabled state as long as the fuel side flow amount 140 is still positive.

In the illustrated example, the actual odorant concentration may continue to decrease to a level that is less than the desired odorant concentration. The processor 304 may continue the first modulation by asserting the maximum flow signal 340A to the maximum flow actuator 228A. This may cause the actual odorant concentration to a point at which it is again equal to the desired odorant concentration. The processor 304 disables the first modulation, thus disabling the maximum flow signal 340A.

With the actual odorant concentration equal to the desired odorant concentration, both the first and the second modulations are disabled. The enable reduced flow 340B signal remains asserted to the reduced flow actuator 228B, and therefore odorant is being produced to the odorized fuel media 168 as long as the fuel side flow amount 140 is positive. At some point, the fuel side flow amount 140 reduces to reflect a zero flow rate. For example, an operator may close the valve 128A. The processor 304, in response, disables the enable reduced flow 340B signal to the reduced flow actuator 228B, and the mixture operation is completed.

Finally, those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiments as a basis for designing or modifying other structures for carrying out the same purposes of the present invention without departing from the spirit and scope of the invention as defined by the appended claims. 

The invention claimed is:
 1. A system, comprising: a fuel media supply, coupled to a fuel media supply flow meter, configured to provide unodorized fuel media; an odorant supply, configured to provide odorant, coupled to: a first actuator, configured to allow odorant flow at a first pressure when enabled; and a second actuator, configured to allow odorant flow at a second pressure lower than the first pressure when enabled; a mixture receiver, coupled to the fuel media supply and the first and second actuators, configured to receive odorized fuel media comprising a mixture of the unodorized fuel media and the odorant; and a control system, comprising: a processor, coupled to the fuel media supply flow meter, the first actuator, and the second actuator; and a memory, coupled to the processor, comprising instructions, that when executed by the processor, are configured to: enable the second actuator to initiate production of the mixture to the mixture receiver; adjust the mixture by selectively enabling and/or disabling the first and second actuators, in response to the mixture does not include a desired concentration of the odorant; and terminate production of the mixture.
 2. The system of claim 1, wherein the first and the second actuators are configured to prevent odorant flow in response to the first and the second actuators, respectively, are disabled.
 3. The system of claim 1, wherein the first and second actuators are disabled before the processor initiates production of the mixture.
 4. The system of claim 1, wherein the processor initiates production of the mixture comprises the processor is configured to: detect a positive flow rate of the fuel media supply from the fuel media supply flow meter, and in response: enable the second actuator.
 5. The system of claim 4, wherein the processor terminates production of the mixture comprises the processor is configured to: detect a zero flow rate of the fuel media supply from the fuel media supply flow meter, and in response: disable the first and second actuators.
 6. The system of claim 1, wherein the processor initiates production of the mixture comprises the processor is configured to: receive data that indicates a volume of the mixture to produce; calculate an odorant volume based on the volume of the mixture to produce and the desired concentration of odorant; detect a positive flow rate of the fuel media supply from the fuel media supply flow meter, and in response: enable the second actuator.
 7. The system of claim 6, wherein in response to the processor enables the second actuator the processor is configured to: enable the first actuator.
 8. The system of claim 6, wherein the processor terminates production of the mixture comprises the processor is configured to: determine a portion of the mixture has been produced, wherein the portion comprises less than the volume of the mixture to produce; disable the first actuator, in response to the first actuator is currently enabled; determine the odorant volume has been provided to the mixture; and disable the second actuator.
 9. The system of claim 1, wherein the processor adjusts the mixture with the first and second actuators comprises the processor is configured to: repeatedly enable and disable the first actuator according to a first modulation until the mixture includes the desired concentration of odorant, in response to the mixture includes a lower than desired concentration of the odorant; and repeatedly enable and disable the second actuator according to a second modulation until the mixture includes the desired concentration of odorant, in response to the mixture includes a higher than desired concentration of the odorant.
 10. The system of claim 9, wherein each of the first and second modulations comprises a signal of fixed duty cycle that alternates between an enabled state and a disabled state.
 11. The system of claim 9, wherein one or more of the first and second modulations comprises a signal of variable duty cycle that alternates between an enabled state and a disabled state.
 12. The system of claim 1, wherein a flow rate of the odorant is proportional to a flow rate of the fuel media supply.
 13. A method, comprising: initiating production of a mixture comprising unodorized fuel media and an odorant by enabling, by a processor coupled to a first and a second actuator, the second actuator configured to allow odorant flow at a second pressure lower than a first pressure when enabled, the first actuator configured to allow odorant flow at the first pressure when enabled; adjusting the mixture, by the processor selectively enabling and/or disabling the first and the second actuator, in response to the processor determining the mixture does not include a desired concentration of the odorant; and terminating production of the mixture.
 14. The method of claim 13, wherein the first and the second actuators are configured to prevent odorant flow in response to the first and the second actuators, respectively, are disabled.
 15. The method of claim 13, wherein the first and second actuators are disabled before the processor initiates production of the mixture.
 16. The method of claim 13, wherein initiating production of the mixture comprising: detecting a positive flow rate of the fuel media supply, and in response: enabling the second actuator.
 17. The method of claim 16, wherein terminating production of the mixture comprises: detecting a zero flow rate of the fuel media supply, and in response: disabling the first and second actuators.
 18. The method of claim 13, wherein initiating production of the mixture comprising: receiving data indicating a volume of the mixture to produce; calculating an odorant volume based on the volume of the mixture to produce and the desired concentration of odorant; detecting a positive flow rate of the fuel media supply, and in response: enabling the second actuator.
 19. The method of claim 18, wherein in response to enabling the second actuator the method comprising: enabling the first actuator.
 20. The method of claim 18, wherein terminating production of the mixture comprises: determining a portion of the mixture has been produced, wherein the portion comprises less than the volume of the mixture to produce; disabling the first actuator, in response to the first actuator is currently enabled; determining the odorant volume has been provided to the mixture; and disabling the second actuator.
 21. The method of claim 13, wherein adjusting the mixture with the first and the second actuator comprises: repeatedly enabling and disabling the first actuator according to a first modulation until the mixture includes the desired concentration of odorant, in response to the mixture includes a lower than desired concentration of the odorant; and repeatedly enabling and disabling the second actuator according to a second modulation until the mixture includes the desired concentration of odorant, in response to the mixture includes a higher than desired concentration of the odorant.
 22. The method of claim 21, wherein each of the first and second modulations comprises a signal of fixed duty cycle that alternates between an enabled state and a disabled state.
 23. The method of claim 21, wherein one or more of the first and second modulations comprises a signal of variable duty cycle that alternates between an enabled state and a disabled state.
 24. The method of claim 13, wherein a flow rate of the odorant is proportional to a flow rate of the fuel media supply. 